Apparatus for casting dental restorations



INVENTOR. IRVING HORDES BY 56,). Q9, (4..)9

A ORNEY I l u 2 Sheets-Sheet l l HORDES APPARATUS FOR CASTING DENTAL RESTORATIONS Feb. 27, 1951 Flled Feb 25, 1948 I. HORDES APPARATUS FOR CASTING DENTAL RESTORATIONS Filed Feb. 23, 1948 Feb. 27 1951 2 Sheets-Sheet 2 INVENTOR. IRVING HORDES A ORNEY Patented Feb. 27, 1951 UNITED STATES PATENT OFFICE APPARATUS FOR CASTING DENTAL RESTORATION S 6 Claims.

This invention relates particularly to improvements in apparatus for use in the casting of dental restorations, that is, in forming a bridge, an artificial tooth or part thereof, such as, an inlay, crown and the like and other dental struc-- tures.

A primary object of the present invention is to produce a novel apparatus which is particularly suited for casting dental restorations using a plastic or other suitable material as the casting material.

Another object is to provide a mold within a flask in which hand packing and automatic pressure combined or automatic pressure alone may be used to condense the plastic material and augment the supply thereof to the cavity in which the restoration is to be formed, thus assuring a thoroughly condensed plastic composition.

A specific object is to provide improved means for clamping the sections of the flask together.

A further object is to provide improved means for sealing the end of the flask.

Yet another object is to provide improved means for hand packing the denture material.

Another object is to provide apparatus of this kind that is easily manipulated, is inexpensive, comparatively simple in construction, is rugged and is readily adjustable to meet any requirements in the casting of dental restorations.

Other objects and advantages of the invention will be apparent from the description thereof to follow taken in connection with the accompanying drawing in which- Fig. 1 is a vertical sectional view of my improved apparatus showing the flask in position on its support and with the sprue forming members in position and carrying a wax pattern which forms the mold in the investment material.

Fig. 2 is a vertical sectional view of the improved apparatus showing the parts in position for receiving plastic material in the mold in the flask and showing apparatus in position for hand packing such plastic material.

Fig. 3 is a view similar to Fig. 2 but showing mechanism in position for automatically pressing the plastic material into the mold.

Fig. 4 is a top plan view of the apparatus of Fig. 3, with the press removed.

Fig. 5 is a side elevational view of the outer sprue member of Fig. 1.

Fig. 6 is a side elevational view of the inner sprue member supporting a wax pattern, parts being shown in section.

Fig. 7 is a side elevational view of the clamping nut.

Fig. 8 is a spread elevational view of the apparatus for hand packing the plastic material, parts being shown in section.

Fig. 9 is a side elevational view of a modified form of outer sprue member.

The plastic material used for making dental restorations should be in a soft but viscous state, that is, about the consistency of putty or a thick paste. Plastic in this condition may be obtained or prepared in two ways. Powdered or granulated plastic in its cured or polymeric form is mixedwith a portion-of the plastic in liquid or monomeric form in a manner known to the dental technicianin' preparing plastic to be used for forming dental acrylicjacket crowns, inlays and the like. The viscous plastic may be obtained also by using polymeric plastic in powdered, granular or biscuit form and heating it until it has the'proper viscous consistency.

The investment material for the casting may be formed in the customary manner using known materials such as plaster of Paris or the like.

Referring to the drawings, a wax pattern It is formed in a known manner after which it'is mountedupon a pin or Wire I l. A cavity forming metal sleeve or outer tubular sprue member [2 is formed with an inwardly tapered neck portion l3 at its upper end providing a restricted opening.

The lower end of the sprue member is formed with an externallyscrew threaded portion l4 and with an integral disc l5 forming a base for the sprue member. The disc has a tapered'peripheral edge Iii. A disc-like support or base I? has a central internally screw-threaded opening it and is provided with an upper peripheral flange IS. The screw-threaded portion M of the sprue member is adapted to be screwed into the threaded opening iii of support I l to seat the sprue member removably on the support IT. The outer surface of the sprue member 12 is formed with angle portions 20 to receive a tool for tighten ng and loosening said sprue member.

Another sprue member is adapted to be positioned inside of the outer sprue member 12 and is formed'with a tubular body portion 2! having a base or flange 22 at its lower end and a tapered neck portion 23 at its upper end. The outer periphery of the flange 22 is formed with screw threads. The body portion is formed with spaced slits 24 extending through the neck portion.

A sectional flask is removably supported on the disc-like base I! around the sprue members. The flask comprises a lower mold section 25 and an upper mold section 26 as viewed in Figure 1, said sections having interlocking flange portions on their meeting edges. The edges may be formed with pry-notches and one section may have a pin 21 on its edge adapted to be received in a notch 28 on the other section to facilitate connection and separation of the sections. The mold sections have tapered inner walls in opposed relation.

To assemble the parts, the outer sprue member i2 is positioned in the bottom of the lower flask section 25 as viewed in Fig. 1 with the tapered edge of disc engaging the inner tapered wall of said section to seal said section at its lower end. The lower section 25 with the outer sprue member mounted therein is placed on the upper surface of the support I! with the outer surface of the wall of said section fitting against the inner surface of flange [9 of the support. The

threaded portion [4 of the outer sprue member will be in position to engage the threads of the opening i8 of disc I! and upon turning of said outer sprue member, said sprue member and lower section 25 will be secured to the support 11. The inner sprue member is then inserted through the opening l8 of support H from the bottom and its flange 22 threaded to the threads of said opening below the threaded portion [4 of the outer sprue member. The upper end of the tapered neck portion 23 of the inner sprue member will project slightly above the upper end of the outer sprue member. With the wax patter l0 secured to the top pointed end of wire H, said wire is dropped through the opening in the neck portion 23 and body of the inner sprue member until the pattern rests on the upper edge of the neck portion where it is held by a spot of wax. The wax pattern is thus held spaced from the upper end of the outer sprue member. The screwthreaded flange 22 of the inner sprue member is set upon by a suitable tool and the sizes of the openings in the tapered neck portions I3 and 23 of the outer and inner sprue members, respectively, are such that when the slitted neck portion 23 engages the wall of the restricted opening in the tapered neck portion l3, said slitted neck portion 23 becomes contracted and grips the wire thereby serving as a chuck member to hold the wire with its wax pattern in proper position.

The sections of the flask may be held in superimposed relation by means of clamping apparatus consisting of a frame formed of a metal casting and having a circular base portion 29 and a circular top portion 30 of smaller dimensions, said base and top portions being connected at their sides as viewed in Fig. 1 by nar row upright arms 3| leaving the front and rear of the frame open. The top portion 39 is formed with a centrally internally screw-threaded opening 32 and removably mounted in this opening is a nut member 33 having internal screw threads and external screw threads 35 with a skirt portion 36 depending from the threads 35. The upper surface of the base 29 is countersunk as indicated at 31. When the support H and supported flask are centered on the base 28 of the frame, the lower edge of the skirt portion 35 of the nut member is in alignment with the upper edge of the uppermost flask section, for instance, section 26 as viewed in Fig. 2 so that upon setting upon the nut member, the support and associated parts are securely clamped in position as shown in Fig. 2, thereby preventing displacement of the parts.

In using the improved apparatus, investment material 38 is poured into the lower section 25 as viewed in Fig. l to or approximately to the upper edge thereof and tapped leaving a portion of the wax pattern ill projecting above said investment material. A coating of separating material may then be applied to the upper surface of the investment material to facilitate separation of the flask sections. The upper section 26 is then filled with investment material in the same manner. The investment material is then permitted to harden. The mold is then placed in boiling water and the wax is melted out. The two sections are separated and the pin H and sprue member 2| removed leaving the outer sprue member l2 embedded in the investment material and forming a cavity or mold 353 in the investment material at the point where the wax pattern ID was and being shaped like said pattern.

A chamber 49 is left inside the outer sprue member l2 where the inner sprue member was and saidchamber 40 and mold 39 are connected by a passage or gate 4! as shown in Fig. 2. The two flask sections 25 and 25 are connected together again after the pin and inner sprue member have been removed and said sections are placed on the base 29 of the frame in inverted position, that is, the section 26 is placed on the bottom and the section 25 with its sprue member i2 placed at the top as shown in Figures 2 and 3, and they are clamped in this position by the nut member 33. It will be seen that disc l5 and the outer sprue member l2 seal the upper end of the flask. The apparatus is now in position to receive the plastic material 42. This material is forced into the cavity or mold 39 through the chamber 43 in the outer sprue member I2. The material may first be tightly packed manually by hand and then stronger pressure may be exerted thereon by suitable pressing apparatus.

In Figs. 2 and 8 is shown suitable apparatus for preliminarily packing the material 42 by hand. This apparatus consists of a tubular member 43 having a narrow central passage 44 terminating at its upper end in a widened chamber 45 and at its lower end in an internally screwthreaded recess 46. The tube is adapted to be inserted through the opening in the nut member 33 and to have its threaded recessed end 46 threaded to the threaded extension I l of the outer sprue member as shown in Fig. 2. The upper end of the tube projects above the upper end of the nut member. The plastic material 42 is placed in the upper chamber 45 of the tube and it is forced through the passage 4 and into the cavity or mold 39 by means of a plunger 41 provided with a knob or handle 48. The material is packed into the mold 39 by means of the plunger 41.

The tube 43 and plunger 41 may be removed and a pressure device mounted in position as shown in Fig. 3 for condensing the plastic denture material. This device consists of a housing 69 having an externally screw-threaded bottom end 50 secured to the inner threaded-portion 34 of the nut member 33. A pressure screw 58 moves in the housing and is provided with a handle 52 at its upper end. The screw brings pressure on the top of a separate plunger member 53, the lower end of which presses down on the denture plastic material in the chamber 42 and mold 30, thus properly filling the mold with denture material and causing the same to be properly condensed. This constant pressure is automatically applied to the denture material within the mold and the operator is free to attend to other work.

When suflicient pressure has been applied, the

entire apparatusis placed'in 'a'hot bath, oven, furnace or the like whereupon the plastic denture material hardens or sets while pressure is retained thereon.

After processing the casting, it is allowed to cool. The sections of the hollow flask are then separated by a suitable tool. The restoration is then removed from the investment and cleaned.

It will be noted that the disc portion l of the outer sprue member 12 seals the end of the flask and keeps the acrylic clean. The disc portion also looks the lower section 25 to the disc I! thereby forming a unitary structure keeping the flask sections immobile and thereby making the pouring of the investment material easier and thereby preventing injury to the pattern.

The nut member 33 clamps the flask sections tightly together and also serves as a bearing for the pressure device.

The flask and associated parts are inserted through the open front or rear of the frame to proper position on the base 29.

It will be seen that the tubular member 43 is so constructed that it can be easily cleaned.

The plunger 3'! may also serve as a signal device to test when the chamber 40 in the sprue member I2 is fully packed with acrylic or plastic material. Such material is elastic or resilient and when the chamber is slightly over-packed the resiliency of the material will cause the plunger to spring back when pressure thereon is released.

In Fig. 9 the outer sprue member I2 is shown formed without the disc portion I5 formed integrally therewith. This form of sprue member can be moved inwardly and outwardly of the flask section in order to adjust the inner position of its neck portion 13 relative to the wider end of the flask section.

Changes in details of construction might be made without departing from the principle of the invention.

I claim:

1. In apparatus of the character described, a disc-shaped base having a central screw-threaded opening, a sectional hollow flask supported on said base above said opening for receiving investment material, an outer tubular sprue member positioned inside said flask, said sprue member having an integrally formed disc-shaped base portion with a tapered peripheral edge and having a threaded extension below said base portion, an inner sprue member extending through said central opening and into the interior of said outer sprue member, said inner sprue member having a central passage, a slitted neck portion at one end projecting outwardly of said outer sprue member and a threaded flange on its other end engaging the threads of said central opening, a pin detachably mounted in said central passage and projecting outwardl thereof and a wax pattern on the projecting end of said pin, the tapered peripheral edge of said disc-shaped base portion engaging the wall of said flask at the bottom end thereof for sealing said bottom end and clamping the flask to the disc-shaped base.

2. In apparatus of the character described, a disc-shaped base member having a central internally screw-threaded opening, a sectional hollow flask supported on said base member above said opening for receiving investment material, an outer tubular sprue member having an externally screw-threaded bottom end engaging the threads of said central opening, an inner sprue member extending through; said central opening and into the interior of said outer sprue member,- said innersprue-member having a-central passage and having a taperedslitted neck portion normally projecting outwardly of the end of said outer sprue member inside the flask,,a pin detachably mounted in said central passage and projecting outwardly of the neck portion into the flask and a wax pattern on the projecting end of said pin, said inner sprue memberhav ing an externally screw-threaded flange extending outwardly of the end of the outer sprue member outside of the flask and coacting with the central screw-threaded opening of said base memher for moving said inner sprue member lengthwise of the outer sprue member whereby said slitted neck portion is pressed into gripping relation with the pin and a disc member formed integrally with said outer sprue member inside said flask, said latter disc member having a tapered outer peripheral edge engaging the inner Wall of the flask at the bottom end thereof for sealing said end of the flask and for locking the flask to the first-named disc-shaped base memher.

3. Apparatus of the kind described comprising a frame having an integral circular base portion, a circular top portion spaced therefrom and having a central internally screw-threaded opening and integral upstanding arms connecting said base and top portions, and a nut member having an externally screw-threaded portion engageable with the threaded opening of the top portion of the frame, said nut member having a skirt portion adapted to extend below the top portion and inwardly of the frame to engage a flask member for clamping such flask member on the base of the frame.

4. Apparatus of the kind described comprising a frame having a circular base portion, a circular top portion spaced therefrom and having a central internally screw-threaded opening and upstanding arms connecting said base and top portions, and a nut member having an exteriorly screw-threaded portion engageabl with said threaded opening in the top portion of said frame, said nut member having a skirt portion adapted to extend below the top portion and inwardly of the frame to engage the end of a flask member for clamping the latter on to the base portion of the frame, said nut member having a central internally screw threaded opening for detachably connecting a screw-threaded material pressing device thereto.

5. Apparatus of the kind described comprising a frame member having a circular base portion, an integral circular top portion spaced therefrom and having a central internally screw-threaded opening, integral upstanding arms connecting said base and top portions, a tubular nut member having an externally screw-threaded portion engageable with the threaded opening in the top portion of said frame and having a skirt portion adapted to extend below the top portion inwardly of the frame to engage the end of a flask member for clamping the flask to the base portion of the frame and material packing apparatus extending through the central opening in said nut member for detachable connection to a portion of the flask.

6. Apparatus of th kind described comprising a frame member having a circular base portion, a circular top portion spaced therefrom and having a centrally internally screw-threaded opening, upstanding arms connecting said base and z sa su m 7 8 'top'portiong-a' tubulapnub memberihaving an ex- REF RE S CITED .temauyScrew-threaded;portlomengageable with The"fb1lowin'g rfe'rences are of record in the thethreadd'opening in the top rpor-tionofthe 'frame an'd having 'a skirt portion adapted-to enfile thls patent gage the endf a flask memberfor-clamping't'he b UNITED-STATES PATENTS fiaSk'onto-the' ba-se portion of 'theframe member, Number Name Date a tubillar member extending inw rdly-'t h 736,279 Franklin Apr. 4 1905 e ce tral opening in Said nut-memben and a 2,279,952 Pryor 1942 m nually operable plunger slidable in saidtubular 2333,833 Tryfus Nov. 1943 member. 10 2,'421;'698 'Hordes June 3, 1947 IRVING ZI'IORDES- 2,442,847 Galley J 3 1943 

